Thanks for the fix!

N.B. we already have isNotEmptyand isEmptyand other such optimised helpers in StringHelper, but it seems that indeed not all code was using these consistently.

Merged the PR.

I'm going to investigate the Spring code as well and probably will open an additional PR for Spring Framework.

Ah, no need to bother. It was simply my oversight. The docs state it clearly:

Note: If the object is typed to String upfront, prefer hasLength(String) or hasText(String) instead.

See https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/StringUtils.html#isEmpty-java.lang.Object-

And hasLenght is equivalent to your nonNullAndIsEmpty

Thank you for the double-check! Yes, org.springframework.util.StringUtils.isEmpty is for Object param, and I don't think I can do much with it, but hibernate should get a bit of performance boost after optimization in common cases. I'm going to investigate the Spring code as well and probably will open an additional PR for Spring Framework. Thank you for pointing it out!

I was a bit skeptical at first, especially bc. of the rational (disseminating equals method), since HotSpot actually has an intrinsic for String.equals, but my own benchmarks confirm these results.

I tried Oracle Java 8 on Ubuntu WSL (Win 10) and AdoptOpenJdk 11 on Win 10. I also added one test case “nullAndPreEquals” which is equal to org.springframework.util.StringUtils.isEmpty (namely (str == null || "".equals(str))` ):

Oracle Java 8 (on WSL):

Benchmark (strParams) Mode Cnt Score Error Units
EmptyStringEquals.equalsPost avgt 20 4.193 ± 0.095 ns/op
EmptyStringEquals.equalsPost nonEmptyString avgt 20 3.255 ± 0.034 ns/op
EmptyStringEquals.nonNullAndIsEmpty avgt 20 2.823 ± 0.176 ns/op
EmptyStringEquals.nonNullAndIsEmpty nonEmptyString avgt 20 2.690 ± 0.128 ns/op
EmptyStringEquals.nullAndPreEquals avgt 20 3.886 ± 0.063 ns/op
EmptyStringEquals.nullAndPreEquals nonEmptyString avgt 20 3.260 ± 0.041 ns/op
EmptyStringEquals.preEquals avgt 20 3.874 ± 0.077 ns/op
EmptyStringEquals.preEquals nonEmptyString avgt 20 3.287 ± 0.060 ns/op

AdoptOpenJdk 11 (HotSpot) (on Windows 10):

Benchmark (strParams) Mode Cnt Score Error Units
EmptyStringEquals.equalsPost avgt 20 4,837 ± 0,076 ns/op
EmptyStringEquals.equalsPost nonEmptyString avgt 20 3,880 ± 0,069 ns/op
EmptyStringEquals.nonNullAndIsEmpty avgt 20 3,020 ± 0,048 ns/op
EmptyStringEquals.nonNullAndIsEmpty nonEmptyString avgt 20 3,202 ± 0,095 ns/op
EmptyStringEquals.nullAndPreEquals avgt 20 4,813 ± 0,120 ns/op
EmptyStringEquals.nullAndPreEquals nonEmptyString avgt 20 3,988 ± 0,197 ns/op
EmptyStringEquals.preEquals avgt 20 4,828 ± 0,093 ns/op
EmptyStringEquals.preEquals nonEmptyString avgt 20 3,949 ± 0,072 ns/op

EDIT: Reading up on StringUtils.isEmpty() I can see that it takes an Object, not a String and that they recommend using !StringUtils.hasLenght() for known Strings (which uses s != null && !s.isEmpty())